The use of congeneric surveying poles for staking out and measuring terrain points are known from prior art, for example from U.S. Pat. No. 7,788,815 B2, EP 1 130 355 A2 or JP 2000 234933. In survey applications using geodetic devices such as TPS equipment, a position measurement is not taken of the target point directly, but rather of the receiver or the antenna on the surveying pole. A conclusion to the position of the target point is possible due to the known spatial relationship between the receiver or antenna, and the tip of the pole. With this method it is possible to circumvent obstacles which stand in the direct way between the measuring instrument and the target point.
To provide further flexibility for such obstacles avoidance, usual practice is the realization of a pole adjustable in its height. As the geodetic instrument and the surveying pole are connected with each other in order to communicate, the pole can be given an indication by the geodetic instrument, when visual contact has been obtained. From that, the pole can give notice to its user by an audible, vibratory and/or visual signal.
Survey pole solutions comprising a GNSS antenna are not reliant on a geodetic instrument as they obtain their positional data via a satellite positioning system. However, to increase measurement accuracy, a GNSS reference station might be provided at the scene. In traditional surveying with a GNSS-pole the surveyor places the pole tip onto the measuring point, levels the pole and triggers the GNSS measurement, the results of which include also height information.
As for the height measurement of the pole adjusted in the described way, current solutions are either manual reading from a tape measure or automatic measurements with a measurement system based on the surveying pole. Conventional, i.e. analogue, surveying poles typically have visual measurement markers (such as a scale and numbers) printed on the pole or on a tape attached to the pole, which makes them operate like an ordinary measuring tape. For this purpose, the poles have a telescopic structure which provides the height adjustability and the measurability by shifting the scale according to the height adjustment.
Other solutions, such as offered in U.S. Pat. No. 7,373,725, provide automatic height measurement using electronic appliances, wherein a reference indicator and a grade-rod reference surface indicating absolute height marks are used for the height detection. Differences in electromagnetic coupling are detected with help of the incremental inductive path detection. Derived from this are a relative movement and a height measurement resorting to this relative distance traveled.
Documents U.S. Pat. No. 7,251,899 B2 and U.S. Pat. No. 7,788,815 B2 further provide a solution for an automatic height measurement for a height-adjustable pole, using a laser distance measurement between a laser sensor mounted at a lower section of the pole, and a lip placed at the top of the pole, the laser sensor and the lip being mounted in a way providing a correlation between the height adjustment of the pole and the separation of the laser sensor and the lip. However, the solution disclosed in these documents leads to a light path being outside of the pole, which for example has the disadvantage of being prone to external disturbances, and thus requiring an enhanced calibration overlay.
Height measuring solutions for surveying poles known from prior art have several common disadvantages. As surveying jobs are subject to a high expenditure of time, known surveying poles do not meet the needed time efficiency requirements, as a high share of manual steps is necessary. Furthermore, even fully or partly automated solutions are often prone to errors caused by outer disturbances and still require a fair amount of expert knowledge. Therefore, due to manual steps and required expert knowledge, common surveying poles allow for too many sources of error caused by the user.